Pioneer SA-8100 Mechanical Issues

[DonQuixote99]

The snap crackle pop had me worried about bad transistors and stuff, but I deoxited the controls, and stuffed some q-tips in next to the protection relay, and all sounds great now.

The Q-tips? Well, I was afraid the sides of it might be shorting out against the chassis. The cover is all busted off, and it's just kind of floating there. I figure the cure for that is some black tape--tape the poor busted cover back onto the base, and then tape the whole thing in.

My main question: the speaker selection control shaft is bent (see a pattern at the left end here?) Anyway, what's a good way to straighten that without risking busting it off?

 

[Watthour]

The switch stem is aluminum, and will snap under stress. Heat will help anneal the material so that it can be moved. Be careful with the application of heat however, since the bushing in the pot housing may be damaged by excessive heat.

As for the relay, it appears you have the Omron part number inked on the cover, so replacement should be easy enough to find or cross reference.

 

[ryuuoh]

The shaft is bent at the bottom of the slot. If you're very gentle, you can wedge a spacer in the slot to get the slot straight, then gently tap with a soft face mallet until the shaft is straight.
It might break, might not. I believe you can buy (for a ridiculous sum) a replacement pulled form a parted out unit.

 

[DonQuixote99]

Looked a while for the relay, but came up dry except for this Hong Kong outfit:

http://www.geocities.ws/sc380/Eng/default_eng.html

I'd have to contact them for price and availability. Might sell in quantity only. OR Oaktree has a pull for $35.00. But the current relay is functional. For now kludging with black tape seems the way to go to me....

For the speaker selector switch, there's a pull on the bay for 24.99/BO. Good to know if my straightening efforts destroy the one I've got....

 

[Watthour]

It seems that the major problem with the relay is the cover (mounting) and not the relay itself. A compatible relay is HERE but it has the generic cover with no mounting tabs. An option might be a chassis mount socket and a standard relay, such as this:

As for the shaft, aluminum melts at between 1100-1200°F Approximately, depending upon the alloy) and anneals at 600-750°F. You only need to get the pot stem close to the 600°F point in order to be able to work it with relative safety. Even getting it closer to that temperature is going to help make it more malleable than trying it at room temperature. Judicious heat with a small torch tip could be just the trick, but keeping the rest of the pot cool enough to avoid damage will be a challenge.

 

[DonQuixote99]

Shaft straightened successfully!

Pic shows small washer inserted into shaft split, which corrected gap and allowed me to then bend it without forcing the halves back together. I think this reduced chance of one of the halves breaking off.

I did heat up it some with a propane torch. What I had was a big 'plumbing scale' torch, but I turned it down to the smallest stable flame, less than an inch long. It probably helped that the tank was nearly empty. The control was worked-on mounted, so the chassis served as a heat sink, as did the pair of long nose pliers I grasped the top of the shaft with. I played the torch on the shaft for about 10 seconds, then grabbed the shaft with a big pair of linesman pliers and bent it straight. Nothing to it!

I've also done a temporary repair to the relay:

 

[DonQuixote99]

It seems that the major problem with the relay is the cover (mounting) and not the relay itself. A compatible relay is HERE but it has the generic cover with no mounting tabs. An option might be a chassis mount socket and a standard relay, such as this:

As for the shaft, aluminum melts at between 1100-1200°F Approximately, depending upon the alloy) and anneals at 600-750°F. You only need to get the pot stem close to the 600°F point in order to be able to work it with relative safety. Even getting it closer to that temperature is going to help make it more malleable than trying it at room temperature. Judicious heat with a small torch tip could be just the trick, but keeping the rest of the pot cool enough to avoid damage will be a challenge.

Thanks for that source, watthour. Looks like just the stuff.

Your advice on shaft straightening was invaluable.

 

[Watthour]

Hey, you fixed it, not me. I've broken them before trying to straighten them cold, even with a shim in the slot and a tube over the entire bent length. That forces this kind of work:

http://www.audiokarma.org/forums/showpost.php?p=4984257&postcount=1

Then I tried the heat method with a pencil tip propane torch (no need to drag the oxy/acetylene tanks into the basement).

The relay socket might fit without trimming, but measure carefully before ordering. A couple of the pros here had remarked that the socket might only fit with some enlarging of the hole in the chassis, and that may require a bit more disassembly. As an alternate, you might be able to use a different relay type entirely:

http://www.audiokarma.org/forums/showthread.php?t=150439